App to predict sun and shade

Want a tree to shade a window at 5 pm on midsummer day? Want to make sure the neighbor's tree doesn't shade your garden site in mid-April? There's an app for that!
Actually, several. Photographers use them all the time to plan photo shoots. I went through my app collection and nothing seemed right for the permaculture crowd, until I found LightTrac.

Here are a couple screen shots, settings are June 21 at 5:30 pm. Question: how big of a tree do I need on the west side of my house to shade my bedroom window:
The first image is shows the length of shadow cast by a 15 ft tree.
The second image shows that at 5:30 the sun is due west (red line), and it is going to set pretty far to the north (blue line).
Going to need a bigger tree.

I have no interest in LightTrac, just found it useful in the field.

Mod: if this belongs in the solar forum, my apologies.
Edited to correct captions.